Uninterruptible power supplies or systems have been used to provide reliable sources of electrical energy to loads, such as electric motors for pumps, in the presence of unreliable or inadequate utility supplied energy. Such supplies, for example, have included rechargeable back-up batteries and AC inverter drive circuits which are activated in the event that the utility supplied power ceases to be available. One such system is disclosed in U.S. Pat. No 5,508,905, entitled, “Low Distortion Variable Output Power”, assigned to the assignee hereof and incorporated by reference herein.
While useful, known systems tend to have limited capabilities. For example, known systems are often fed from single phase AC and are intended to drive single phase loads, such as single phase motors. Not only is there limited input flexibility, known systems often are designed to drive a single electrical output. Driving multiple loads has often required multiple supplies. In addition, input electrical sensing capabilities have been limited to sensing the presence or absence of input AC and not the quality of the available energy.
There is a continuing need for uninterruptible power supply systems which can be driven from multi-phase utility power, for example three phase power, and which can automatically switch and drive multiple loads. It would be desirable to be able to evaluate the quality of incoming energy to determine if it is sufficient to energize the loads. It would also be desirable to be able to load or modify the parameters of such systems locally from another computer or remotely, via an electronic network such as the world wide web. Finally, it would be desirable to incorporate software and one or more programmed processors in such systems to minimize costs and maximize system flexibility.